Jacuzzi Bus IV

[skylinelimo]

one more bit of info: when I was looking at things, the batteries were on the chargers despite both of them the batteries were fully charged via a green light. (the charger was in auto mode.) At regular time intervals, one of the batteries made a faint girgle sound, and after about three times of that happening, I noticed that green light on the charger which was connected to it, would go off during this. But as soon as the girgle stopped, the green "charged" light would go back on.

never seen that happen before and not really sure what could cause that.

[the_experience03]

Sulfation would cause that...as a result of repeatedly being drawn too low. The plates in the batteries become "coated" making their available surface area much smaller which results in much reduced capacity. On top of that, their internal resistance goes sky high so an automatic battery charger will often see that the necessary voltage to over come the resistance and flow current becomes high. Some chargers will simply call them fully charged at this point. Others will go into a "sulfation mode" and try and knock it off. This is where things are going to get interesting. Your batteries are not that old so the sulfation is not a result of simply sitting around (assuming you never let them sit stone dead long and I don't think you do). So what's the other possible cause? A lack of being fully recharged by the charging system which leads us back to the alternator possibly!

When they test your batteries I would suspect they will load test them with a carbon pile and/or use a conductance tester. Both have their high points and low points. The carbon pile will physically load the batteries. This is great because it replicates what starting batteries typically see. There is no interpolation of results and such. Either it can supply the current or it can't. However, this method is not necessarily terribly accurate for deep cycles which see a lower load drawn out over a longer period of time. Conductance testers often have the capability of interpolating these results because they measure the internal resistance of the battery. Unfortunately, no real load is placed on the battery and though internal resistance testing should catch sulfation, the results are interpolated which means there is room for error.

In a case like this I like to rely on the good old fashioned 3 minute charge test. The great thing is you can do it yourself. Disconnect the cables from the batteries. Place a charge on them and set it to a 30-40 amp charge rate. Watch the clock and after 3 minutes stick your voltmeter leads across the battery terminals while the charger is running. If you see a voltage higher than about 15.5 volts then the batteries are sulfated and replacement is the only real solution. It would also make the charging system and connections very suspect.

*edit* Being that the batteries are 4D's they should be traditional "maintenance" type batteries requiring you to remove the caps and add distilled water to the electrolyte to a level just covering the plates while leaving a small air gap at the top. Have you checked this? Heavy discharge and charging causes the water component to boil out of the acidic electrolyte solution.

[skylinelimo]

I haven't checked the level you mention. However, I did notice, at one point, that one of the caps on a battery was very loose, almost fully backed off of the thread.

[Jarlaxle]

Originally Posted by lapeer20m

he claimes it was a highway bus owned by the city of gainsville florida. I'm pretty sure it was a city bus. It'll cruise about 60 on flat ground. I was never able to get the bus over 65 even going downhill with the pedal to the floor. There are some pretty steep hills between arizona and michigan.

I really like the bus, and 60 mph is acceptable, I'm just disappointed because i was expecting 70 or 80. A bus with a top end of 80 should cruise real nice without having to work at 60 mph.

I"m also surprised how wimpy that 6v71 is. 426 cubic inches, a blower plus turbo, and twice as many power strokes as a four stroke engine. I would have thought that it would be a great match for a 20K pound bus. It's about as anemic as my old 6.6 litre Brazilian. It starts great, blows very little smoke, runs like a top. The motor appears to be in excellent shape. She leaks oil, but i think that's par for the course for a DD. Most of the oil appears to leak out of a pair of hoses under the motor. About 1 gallon every 1K miles. Not like that dt360 in the last bus that didn't use/leak barely a drop of oil.

It sounds really cool! especially when taking off from a stop. I should make a recording of that. The air ride is really nice too, but leaks like a sieve. (sp?) Not a big deal though, it's just plumbing. I'll get working on that as soon as i park the bus indoors out of the snow. It has air everything which is a little bizarre: throttle, engine shutoff, windshield wipers, doors, seat, brakes, suspension and who knows what else.

The body doesn't have a speck of rust. Only rust i've found is on the platform where the a/c unit used to live above the engine.

The oil from the slobber tubes is normal. Very important: DO NOT USE MULTIWEIGHT OIL IN THIS ENGINE EVER UNDER ANY CIRCUMSTANCES!!!! Straight SAE30 OR SAE40 ONLY! Also, don't lug it, don't idle it, and don't ever run it low on oil!

The 6V71 varied from really wimpy to a fire-breather. In transits, many were derated...the 2-valve 6V71N in the old GMC I drove was about 165-175HP. A typical tune was about 225-250HP, with 238 the most common (a "238 Detroit" is a 6-71). In fire trucks, a 6-71TA or 6V71TA could top 300HP easily. I drove another bus with a turbo 8V71 with about 275HP...my uncle drove a GMC General semi tractor with another 8V71 that was turned up, and that smoke-belching monster was well over 500HP.

[skylinelimo]

What kind of antifreeze would this detroit diesel take? standard green I suppose? Is the fill cap on top of a large boxy reservoir that has a mechanical pressure clasp? It is virtually empty but the engine hoses do have coolant in them. There is some slimy nasty stuff in the bottom of the reservoir that I don't know exactly what to call.

[skylinelimo]

Having a bit of electrical problems with the coach inverter/alternator/battery setup. As shown in previous construction posts, this bus has a 24V, 3000W inverter. It is connected to two daisy-chained 12V 4D batteries (less than 6 months old). I've had a problem with the power tripping off after about 45 minutes under near-full electrical load while the bus is in transit. Testing last night on the 24V 165A alternator suggested all is fine with it (had to disassemble and clean the brushes on the other 12V engine/accessory alternator which was not working at all beforehand -- but now it works, yea!). Another discovery during testing was that when the 24V setup is under near-full electrical load (stereo, jacuzzi, lights on, minus the A/C), the (-) battery terminal on the one battery that is grounded to the back body panel gets EXTREMELY HOT (hot enough to make skin smoke!). The battery itself seems fine because it doesn't get hot and the other battery that is connected in series doesn't get hot either. It's just that one terminal that gets really hot. The battery terminal connectors are going to be replaced since they need to be, but is/are there other things that might be causing this? The inverter immediately goes into "overload" when it is first turned on, but with the press of the reset button, it seems to operate fine. Any thoughts/ideas would be greatly appreciated!

[paul iossi]

heat in an electrical circuit is caused by resistance, either a dirty/bad connection or undersized wiring devices, i would suggest that you replace your battery cables with 2.0 welding cable and either properly soldered or crimped terminal ends.

[skylinelimo]

yeah there are big cables on there. the ones going to the inverter appear to be welding cables - they are probably 3/4"+ diameter. Putting on all new terminal connectors and landing the ground onto the chassis (instead of the body panel) today.

[paul iossi]

make sure to run a large jumper from the body to chassis ground

[skylinelimo]

After totally revamping all the connectors and making a good ground connection to the chassis, there is no more scalding hot battery terminal. The 165amp 24V alternator increases voltage across the series-connected 12V batteries from the low 24s to almost 25V when the engine is revved.

[paul iossi]

excellent work
as they say the devil is in the details most maintainence/repair issues can be tracked back to the little stuff that didn't get done or didn't get serviced on a routine basis.

[lapeer20m]

Originally Posted by skylinelimo

After totally revamping all the connectors and making a good ground connection to the chassis, there is no more scalding hot battery terminal. The 165amp 24V alternator increases voltage across the series-connected 12V batteries from the low 24s to almost 25V when the engine is revved.

glad to hear it!

[skylinelimo]

got the A/C working again. spoke with the manufacturer and they said that on hot days (I would say Texas qualifies haha), it will draw up to 2.5x the normal operating wattage of 1147W. so looking at putting it on it's own inverter (onto the chassis batteries) since with the jacuzzi alone, that would push the load over 3000W, the size of the coach inverter.

not sure yet if the alternator would need to be upsized, or if the existing one will help enough; most runs don't last more than 6 hours or so, assuming the a/c is on 100% of the time.

[the_experience03]

Or...you could add another battery bank and a second 24 volt alternator. Hear me out on this now. Using the coach batteries and charging system for such a high demand device is a bit scary in that it leaves you without redundancy. It would take nothing for that AC to kill the coach batteries, even with the alternator running at full tilt boogie (which, coincidently, will drastically shorten its life). To get 3000 watts out of a 12 volt alternator it will need to be CONSTANTLY pushing 250 amps of current. That's A LOT and it doesn't include the other essential demands like headlights and the like.

So...a dedicated alternator for the AC might be best given the fact that this is a commercial application. So why 24 volts? A 24 volt alternator (and inverter) will produce the same amount of power, but at half the current of a 12 volt system. Current is what makes your heat and heat is what kills alternators so this is obviously a good thing. It is also far easier on the brushes as higher voltages transfer power much more effectively. On top of that, the wiring to handle a continuous 125 amps is FAR easier to deal with than the Golden Gate Bridge sized cables required to handle 250 amps. On top of that, battery connections will do far better at that lower load. 250 continuous amps of current will melt the threaded insert right out of a side post battery. Top posters like you have are a little more robust, but that doesn't mean the heat isn't taking its toll.

Just my $.02

[skylinelimo]

hmm yeah I thought of getting another set of batteries but (1) where to put them...and could probably figure that out, but (2) this means a third alternator?

[lapeer20m]

i'm sure that the jacuzzi takes far less current to run than the A/C unit. Why not run just the A/C unit off from the current 24 volt alternator/inverter setup and run the jacuzzi off of it's own 2000 watt inverter from the house batteries?

I don't know/recall the power requirements of the jacuzzi pump, but i would immagine it is 1.5 hp or less.

Another great option that is a little less straight foward is to replace the jacuzzi pump with a smaller less demanding pump. This may affect the time it takes to heat the jacuzzi water, but a heat exchanger could also be added which would heat that quantity of water almost on demand.

i appologize that the current setup isn't working as intended.

Other expensive options are:

an a/c compressor that runs off from the engine, just like you have in a car or other limo's

they make 10K watt hydraulic generators that will run off of the buses engine. We use these on fire trucks. They give you constant power regardless of enigne speed....mostly.

I have been given my lay-off notice and should be unemployed started may 1st. I wish texas wasn't so far away or i'd try to just cruise down there to help figure things out. IF you purchase Jacuzzi bus V maybe we can work out a deal where i deliver the bus to you and while i'm at it help reconfigure the electrical system on jacuzzi bus IV.

[skylinelimo]

I like the heat exchanger idea, depending upon the price of one of those and the difficulty to implement at the jacuzzi's current location. You have any, or know where I can get one cheap? Perhaps it's not much more than drilling a couple holes in the floor and routing it towards the engine. The pump is a 1.5horse, a little over 1.1kW. I've put a fog machine in there (400W) and a couple laser machines (~50W each). Of course you have the TV and stereo and ceiling lights. (are those LED ropes?) In the meantime, I've just heated the tub a day or so in advance, and just disconnected it during a run, which gets us through without any overloads but only the occasional "yea! turn the jacuzzi jets on!". Could continue to do that, but would rather everything be on and operating like it should with good headroom left for the inverter(s).

[lapeer20m]

i buy my heat exchangers from ebay...there is one on there with buy it now for $85 with free shipping

http://cgi.ebay.com/Brazed-Stainless...3A1%7C294%3A50

you don't need a very big heat exchanger for the jacuzzi application. You could easily tap into the coolant lines that run to the rear heater, then just run a 1" ID hose from the jacuzzi pump to the heat exchanger and back. I don't know how to make it work with the current pump, since it's high power. (i guess you could tap into that little quarter inch ID hose that is currently wound around the motor, but it woudl take a long time to heat things up with because you would be moving such a small quantity of water through the tubing) I would suggest buying a cheap pump from harbor freight. This one is only about $40 bucks. I've used these exact pumps in several jacuzzi applications and had pretty good luck. One wierd thing about them is that if they sit for long periods of time with no water in them (2 weeks or so) you have to turn the motor by hand a few revolutions before you start it up or else it won't turn. There is even a warning in the instruction manual that tells you to do just that. I've run one of those for a week straight in the desert at burningman just to filter water, and for extended periods on jacuzzi's in 3 separate buses.

http://www.harborfreight.com/cpi/cta...temnumber=1479

I think it takes about 7 amps @ 110 volts to run the pump.

I'd be more than happy to do all the work of installing the new jacuzzi system for free if i actually get laid off from my job and we can find a way to get me to texas. A 2K watt inverter is about $200 bucks, plus the pump and the heat exchanger, some plumbing fittings and 1" ID heater hose prob works out to less than $500 in parts. With the smaller pump you do loose the good jet action in the jacuzzi, but you still have the ability to heat/filter water while in transit.

here is a 2k watt inverter for $178
http://www.harborfreight.com/cpi/cta...emnumber=92464

The new 2K watt inverter and stock bus alternator shouldn't have to work too hard to run the 1/2 hp pump, plus a few other things. I would save that giant military inverter for the a/c unit.

[the_experience03]

Originally Posted by lapeer20m

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The new 2K watt inverter and stock bus alternator shouldn't have to work too hard to run the 1/2 hp pump, plus a few other things. I would save that giant military inverter for the a/c unit.

2000 watts is ~160 amps at 12 volts. My alternator is only rated at 130 amps and to expect any more than 100 amps out of it on a constant basis would be pushing it. Have you just had the good fortune of getting buses with rugged and manly alternator ratings?

[lapeer20m]

I usually upgrade the alternators on all my buses to 160 or 200 amps. There is a local alternator shop that does the work for me. I've seen 300 amp alternators, but they are really pricey!. I agree that 2000 watts is a lot to ask of a 12 volt alternator, but a motor rated for 700 watts (about 5.8 amps at 120 volts, or about 50 amps @ 14 volts) would be the primary electrical load. An alternator is able to keep up with that pretty easy. I've used that setup for 30K miles. I've also replaced a couple of alternators along the way.